Rust preventive composition



Patented Oct. 26, 19.48

aus'r raevnn'rrva comosmox Herman D. Kluge, Wapplngers Falls, and John A.

Patterson, Newburgh, N. Y., asslgnors to The Texas Company, New York, N. Y., a corporation of Delaware 1% Drawing. Original application November 5,

1943, Serial N0. 509,122. DlVidGd and 1118 application July 18, 1947, Serial N0. 762,008

8 Claims. (Cl. 148-6.].5)

This invention relates to a method of preventing or retarding the corrosion of metals or alloys when in contact with hydrocarbon oils, fatty oils, fatty acids, mineral oils, and other types of compositions which promote corrosion or rusting of metallic surfaces, either per se, or in the presence of water or other chemically reacting substances.

This is a continuation of our pending application Serial No. 509,122, filed November 5, 1943, now abandoned.

The corrosion and/or rusting of metallic surfaces presents a serious problem in the transportation and storage of petroleum products, fatty acids and fatty oils, in the maintenance and preservation of metallic parts and structures subjected to atmospheric conditions, and in the lubrication of industrial machinery, engines, turbines, etc. Accordingly, it is the purpose of the present invention to provide a novel corrosion inhibiting or anti-rusting composition which may be applied to the metallic surfaces in a suitable extraneous medium, or may be incorporated in the lubricating composition, hydrocarbon oil, fatty oil, etc., which is in contact with the metal surfaces.

It has been generally recognized that aliphatic monoand dicarboxylic acids, and particularly I the dicarboxylic acids, possess advantageous antirusting properties for certain types of service. It ,has been found, however, that the anti-rusting properties of the dicarboxylic acids, such as an alkyl maleic acid, are very limited in application and do not afford satisfactory protection of metallic surfaces from the rusting action of salt water. Furthermore, these acids possess certain deficiencies which do not allow their general application to all types of services in which protection of metals from corrosion or rust is desired.

It has now been discovered that" the combination of a dicarboxylic acid and an alkyl acid ester .of an acid of phosphorus provides an improved rust inhibitor which efiectively inhibits rust formation of metallic surfaces even in the presence of salt water. This inhibitor combination may either be incorporated in an oleaginous vehicle for the purpose of providing an anti-rusting composition which is applied directly to exposed metal surfaces, such as steel structures and metal equipment in open air transport and storage, or the inhibitor may be incorporated in the body of a hydrocarbon oil, lubricating composition or other oleaginous substance which normally iscorused with advantageous results.

rosive per se or eflects corrosion or rusting ofth E metal surfaces in the presence of water.

Examples of the various uses to which this inhibitor may be applied are in the preparation of arious rust-proof compounds which are sprayed or brush-applied to exposed metal parts to preserve the surfaces from the corrosive action of various corroding agents, such as acidic gases, salt water, etc; incorporation in corrosive oils, fats and fatty acids for the protection of metallic containers used in the transportation and storage thereof incorporation in hydrocarbon oils, such as gasoline or crude oil which contain small amounts of water in solution, for the protection of drums, tanks and pipe lines used in the transportation and storage thereof; incorporation in various greases, lubricating oils, and miscellaneous lubricants used in the lubrication of mechanical parts of industrial machinery, engines and turbines, for the protection of metal surfaces lubricated therewith which are normally susceptible to corrosion or rust formation in the presence of certain acidic bodies and/or water built up or collected under various service conditions.

It is to be understood that the term oleaginous vehicle, as used throughout the specification and claims, is meant to include all the various oils, fats, fatty oils, fatty acids, greases, lubricants, rust-proof bases, etc., in which the subject inhibitor may be incorporated to protect metal sur faces from corrosion or rust formation.

The amounts of the individual components of this inhibitor combination incorporated in the oleaginous vehicle will vary according to the type of protection and surface to which it is applied. In general, it may be stated that'amounts not materially greater than 3% by weight of the dicarboxylic acid, and not materially greater than 5% by weight of the alkyl acid ester of an acidof phosphorus in the oleaginous vehicle may be In most instances these amounts may be decreased substantially and still provide adequate protection.

Ranges of proportions between dill-12.0% by weight of a dicarboxylic acid and 0.0001-1.0% by weight of an alkyl acid ester of an acid of phosphorus are particularly desirable in lubricating compositions where maximum rust protection and minimum interference with the lubricating propfixed configuration.

The invention broadly contemplates the use of any dicarboxylic acid which contains at least carbon atoms in the molecule and at least one carbon atom between the carboxyl groups, and particularly the high molecular weight acids which are either soluble or miscible in the oleaginous vehicle. Such acids include the derivatives of aromatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and aliphatic dicarboxylic acids.

For the purposes of this invention, these acids may be considered as being into two groups, (1)

dicarboxylic acids which exist in stereo-isomericform; and (2) dicarboxylic acids which possess a It has been found that the greatest rust protection is obtained from an inhibitor combination in which the carboxyl groups of the dicarboxylic acid component are in a plane symmetrical configuration. In the case of the stereo-isomeric acids, this configuration is easily recognizable as the cis form of the acid. As examples of the type of acids falling within these classifications may be mentioned alkylated phthalic acid, alkylated hexahydrophthalic acid, alkyl malonic, alkyi maleic acid and alkyl citraconic acid.

In itspreferred form the invention contemplates a dicarboxylic acid obtained by the'condensation of an olefin with maleic acid anhydride followed by hydrolysis. The acids produced by this condensation reaction may exist as an alkyl maleic acid, an alkenyi succinic acid, or mixtures thereof. In order to simplify the description of these condensation products and the acids produced thereby, they will be described throughout the specification and claims as being alkyl maleic acids.

In preparing these alkyl maleic acids, in accordance with the above-mentioned reaction. the condensation is carried out with an olefin, either straight or branched chain, containing at least six carbon atoms, or mixtures of olefins whose average carbon content is at least six, such as Gin-Cm olefinic mixture. These olefins may be obtained from any of the usual sources, such as vapor phase cracking of petroleum oil or wax, or

the polymerization of lower molecular weight olefins.

The second component of the inhibitor combination, namely, the alkyl acid ester of an acid phosphorus, embraces any alkyl ester of a phosphorus acid which contains atleast one replaceable hydrogen linked to the phosphorus through an oxygen atom, and particularly such alkyl es-- ters as are soluble or miscible in the oleaginous vehicle. The acids of phosphorus whose alkyl acid esters satisfy the requirements of the present invention are the various phcsphoric'acids, which include the ortho, meta and pyro acids, together with the polymeric forms thereof. It is particuleast 10 carbon atoms in the ester radicals therel 4 of. These alkyl, acid phosphates may be prepared by any of the known methods of synthesis and may consist of mixed alkyl esters, such as butyl lauryl acid ortho-phosphate or mixtures of monoand di-substituted esters, such as monoand dl- 48 hours, after which time the steel specimen is I removed, allowed to drain, and washed with precipitation naphtha or hexane and the amount of corrosion or rust observed.

The synthetic sea water added to the test all is made up of the following composition:

Gms. per liter Magnesium chloride (Mg casino) 11.0 Anhydrous calcium chloride (CaCla) 1.2 Anhydrous sodium sulphate (Na2SO4) 4.0

Sodium chloride (NaCl) 25.0

In this particular test a solvent-refined, acidtreated and filtered lubricating oil was used as the reference oil and the inhibitor combination was composed of an alkyl maleic acid and a commercial alkyl acid phosphate. The alkyl maleic acid was prepared by the condensation of maleic acid anhydride and a polymer gasoline distillate, boiling point 385-400 F. The reaction was obtained by heating with agitation for 18 hours and maintaining the liquid at a gentle reflux, initial temperature 324 F., final temperature 360 F. After the heating was complete the reaction product was allowed to cool and fractionated under diminished pressure to remove unreacted polymer and low-boiling reaction products. The alkylated maleic acid anhydride was then heated at 220-240" F. with stirring for four hours in the presence of an equal volume of water. When hydrolysis was complete, the product was extracted with gasoline, washed with water and the solvent evaporated. The resulting alkyl maleic acid possessed a Neut. No. of 359 and a Br. No. of 39. The alkyl acid phosphate used in the test was a commercial product consisting of a mixture of a mono-and di-lauryl acid ortho-phosphate which had an average Neut. No. of approximately 264 and contained an average of about 9.2% phosphorus.

The results obtained in the aforementioned rusting test are tabulated below:

Appearance of steel specimen Reference oil rust-thick coating of rust Reference oii+0.0l% alkyl maleic acid 30% rust. Reference oil+0.0025 lauryl acid ortho-phosphate 100% rust. Reference oil+0.01% alkyl maleic acid, -i-0.il025% lauryl acid ortho-phosphate Clean-no stain bright strip.

It will be seen from the results obtained that each of the individual components of the inhibitor combination, when used separately, provides little or no rust portection in the presence of salt water, but when combined, in accordance with the invention, provides complete protection of the test specimen.

Additional test results have indicated that an alkyl maleic acid prepared by the condensation of maleic acid anhydride and a polymer gasoline distillate of higher and lower molecular weight than that used in the above test, may be combined with other alkyl acid esters of an acid of phosphorus, such as isoamyl octyl acid orthophosphate, butyl lauryl acid ortho-phosphate, dilauryl acid pyrophosphate, etc. and provide inhibitor combinations which, when tested in the modified ASTM rusting test using synthetic salt water, also gave exceptional rust protection of the test specimen.

It is to be understood that the invention is not limited to the specific examples mentioned above, but also includes the combination of other compounds falling within the scope of the invention as set forth in-the specification and claims. Furthermore, the inhibitor combination may also be used in conjunction with other addition agents, such as oxidation inhibitors, pour point depressors, oiliness agents, extreme pressure agents, color stabilizers, V. I. improvers, etc., without departing from the spirit of the invention.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

What we claim is:

inhibiting rust formation of metal surfaces in the presence of salt water which comprises an oleaginous vehicle and the combination of 0.01-3.0% by weight of an oil-miscible dicarboxylic acid containing at least 10 carbon atoms in which the carboxyl groups are in a plane symmetrical configuration, and 0.0001-5.0% by Weight of an oil-miscible alkyl acid total of at least 10 carbon atoms in the alkyl proportions thereof.

3. A rust-preventive composition capable of inhibiting rust formation of metal surfaces in the presence of salt water which comprises an oleaginous vehicle and the combinationof 0.01-3.0%

1. A method of preventing rust formation of metal surfaces in the presence of salt water which comprises applying to metal surfaces an oleaginous vehicle having incorporated therein a combination of 0.01-3.0% by weight of an oil-miscible dicarboxylic acid containing at least 10 carbon atoms in which the carboxyl groups are in a plane symmetrical configuration, and (MOM-5.0% by weight of an alkyl acid phosphate in which the alkyl portions thereof contain a total of at least 10 carbon atoms.

2. A rust-preventive composition capable of by weight of an oil-miscible alkyl maleic acid containing at least 10 carbon atoms, and 0.000l-5.0% by weight of an alkyl acid phosphate in which the alkyl portions thereof contain a total of at least 10 carbon atoms.

4. A rust-preventive composition according to claim 2, wherein the oil-miscible dicarboxylic acid is a condensation product of maleic acid anhydride and an olefin having at least 6 carbon atoms in the molecule.

5. A rust preventive composition according to claim 2, wherein the oil-miscible dicarboxylic acid is a condensation product of maleic acid anhydride and an olefin having at least 10 carbon atoms in the molecule, and the oil-miscible alkyl acid phosphate is a lauryl acid ortho-phosphate. 6. A rust-preventive composition according to claim 3, wherein the alkyl acid phosphate is a lauryl acid ortho-phosphate.

- '7. A rust-preventive composition according to claim 3, wherein the alkyl maleic acid is a condensation product of maleic acid anhydride and an olefin having at least 10 carbon atoms in the molecule.

8. A rust-preventive composition according to claim 3, wherein the alkyl maleic acid is a condensation product of maleic acid anhydride and a high boiling polymer gasoline fraction, and the alkyl acid phosphate is a lauryl acid orthophosphate.

HERMAN D. KLUGE. JOHN A. PATTERSON.

No references cited.

phosphate containing a 

